1. Field of the Invention
The present invention is related to a shoe, and particularly an alpine ski boot, adapted to be retained during support on a gliding surface, in a manner such that it can be freed. It likewise relates to a pair of boots.
2. Description of Background and Material Information
An alpine ski boot is generally retained in support against a ski by front and rear binding elements. Each binding element has a retention jaw which is movable against the return force of a spring, so as to free the boot beyond a predetermined bias threshold.
In the past, a shoe was provided to function with binding elements of a particular type. For example, U.S. Pat. No. 3,709,509 shows a boot whose tips have a projection which cooperates with a corresponding recess in the jaw of the binding element. Such boots could only be utilized with specific binding elements.
More recently, a standard defining the shape of the front and rear tips of the boot has been adopted. In the ISO Standard, this standard is identified under No. ISO 5355.
According to this standard, the tips of the boot which include the end of the sole and the lower portion of the upper have a symmetrical form with respect to a vertical and longitudinal plane.
This form thus defined can be associated with different models of binding elements. Furthermore, it can equally be used with one or the other of the two skis of a pair.
Thus, in the course of skiing, for a torsional bias of the boot corresponding to a lateral release of the front tip out of the front binding, the bias threshold beyond which the binding element frees the boot is the same as the torsional force, tends to make the boot go out towards the interior of the foot or towards the exterior.
Now, it is known that the knee of a human being is more or less resistant to a torsional bias exerted on the leg, along the direction thereof. In particular, the knee is more fragile for a rotation of the foot towards the interior, i.e., towards the other foot.